1. Field of the Invention
The present invention relates to a disc cartridge for discs in general such as a magneto-optical recording medium (hereinafter as magneto-optical disc), and a disc unit to which such a cartridge is mounted.
2. Description of the Background Art
A disc cartridge for a magneto-optical disc will be described as an example of a conventional disc cartridge. FIG. 6(a) is a top plan view of the disc cartridge as an example, and FIG. 6(b) is a bottom view thereof. The shutter is open both in FIGS. 6(a) and 6(b).
In FIGS. 6(a) and 6(b), the disc cartridge 2 comprises an upper shell 3, a lower shell 4, a shutter 8. In the disc cartridge 2, a magneto-optical disc 1 recorded with information signals is rotatably stored. The upper shell 3 has a first opening 5 to which a magnetic head (not shown) for recording/reproducing information signals faces. The lower shell has a second opening 6 to which a spindle motor (not shown) for rotatably holding the magneto-optical disc 1 faces, and a third opening 7 to which a pick up unit (not shown) for recording/reproducing information signals faces.
The disc cartridge 2 described above as a whole is mounted into a magneto-optical recording/reproducing apparatus for recording/reproducing information.
A top loading method, one method of mounting such a magneto-optical disc to a magneto-optical recording/reproducing apparatus, will be now described in conjunction with FIG. 7.
A spindle motor 13 and a cartridge holder 12 which holds and mounts the disc cartridge 2 are provided at the main chassis 10 of the magneto-optical recording/reproducing apparatus. The cartridge holder 12 has an approximately box-like shape, and has an opening at a backward side in the direction for inserting the disc cartridge 2 (the X-direction side in FIG. 7) so as to insert the disc cartridge 2. The rotation supporting point 16 of the cartridge holder 12 is provided at a forward side in the direction for inserting the disc cartridge 2 (the Y-direction side in FIG. 7), and the cartridge holder 12 may be rotated so as to attach/detach the disc cartridge 2 to/from the apparatus. The main chassis 10 is provided with a reference shaft 11 which has its positional relation to the spindle motor 13 controlled, and the reference shaft is fitted into a reference hole 9 provided at the disc cartridge 2 for positioning.
The disc cartridge 2 is loaded as follows. As the cartridge holder 12 is uplifted, the disc cartridge 2 is pressed and inserted tightly into the inside of the cartridge holder 12 to the abutting end, and then the cartridge holder 12 is gradually lowered so that the reference shaft 11 and the center hole of the magneto-optical disc 1 are fitted to the reference hole 9 and the rotary shaft 14 of the spindle motor, respectively. Thus, the loading is completed.
The reference shaft 11 described above has a tapered tip end, and therefore even in the case where the disc cartridge 2 is not sufficiently pressed in, the reference hole 9 of the disc cartridge 2 can slide along the tip end of the reference shaft 11, so that the cartridge can be mounted to the apparatus.
In the disc cartridge 2 loaded in the above described manner, a turntable 15 is inserted to the second opening 6. The second opening 6 is formed in a circular form centered on the standard rotation center of the magneto-optical disc 1, and the size is set to a minimum necessary size slightly larger than the turntable 15 in consideration of errors which may occur in attaching the spindle motor 13 in the apparatus, errors in positioning the disc cartridge 2 to the apparatus, or deviation or variation of each part, as well as a problem associated with the strength of the disc cartridge 2.
In the conventional disc cartridge and the magneto-optical recording/reproducing apparatus described above, if the disc cartridge 2 is not sufficiently pressed in, the second opening 6 of the disc cartridge 2 can collide against the tip of the turntable 15 of the spindle motor 13 as the disc cartridge 2 slides along the reference shaft 11 of the main chassis 10 (part A in FIG. 7).
Particularly in the case of a compact disc cartridge standard having a small thickness with the turntable 15 of the spindle motor 13 being located at a high position, the height of the reference shaft 11 of the main chassis 10 is restricted, and therefore the disadvantage as described above is more likely to be encountered.
The present invention is directed to a solution to the above problem, and it is an object of the present invention to provide a disc cartridge and a disc unit which allow the disc cartridge to be smoothly loaded.
The present invention provides a disc cartridge comprising a disc and a cartridge for rotatably storing the disc and having an opening provided in a region including a position corresponding to a predetermined rotation center of the disc, wherein the opening is offset in a forward direction of inserting the disc cartridge from the position corresponding to the rotation center.
The present invention provides a disc apparatus comprising a disc cartridge at least including a disc and a cartridge rotatably storing the disc, and a disc driving body having a turntable and mounting the disc cartridge, wherein the disc driving body includes a shaft and a cartridge holder, the cartridge has a reference hole for positioning the disc cartridge at the mounting of it, the cartridge holder having a pivoting point and an opening which is formed on a backward side along a direction of inserting the disc cartridge from the pivoting point, and turning on the pivoting point to allow the turntable to be fitted into the opening and the shaft to be inserted in the reference hole.